Electronic and thermal properties of germanene and stanene by first-principles calculations

The electronic, vibrational and thermal properties of germanene and stanene have been investigated based on density functional theory (DFT) and density functional perturbation theory (DFPT). The electronic band structure, total and partial density of states and phonon dispersion spectrum and states are analyzed. The phonon spectrum is positive for all modes in the first Brillouin zone and there is a phonon energy band gap between acoustic and optical modes which is around 50 cm−1 for both structure. The constant-volume specific heats of two structures are calculated by using phonon spectrum and density of states. The spin–orbit coupling (SOC) opens a direct energy band gap at the Dirac point, softens phonon spectrum and decreases phonon group velocity of ZA mode. We investigate the electronic and thermal properties of germanene and stanene. [Display omitted] •A DFT and DFPT study of germanene and stanene is presented.•The intrinsic spin-orbit coupling opens electronic band gap, softens phonon and re-normalizes group velocity in ZA mode.•The specific heat varies as T2 for low temperature limit.•Due to the phonon gap between acoustic and optical branches both structures are applicable for nano-resonators.